William I, Count of Hainaut

Duke Willem III of Holland (1286-7 June 1337) was the Duke of Holland from 1304 to 1337, succeeding Duke Jan II of Holland and preceding Duke Willem IV of Holland.

Biography
Willem was born in 1286 to the House of Avesnes, and he was the son of Duke Jan II of Holland and Philippa of Luxembourg. In 1304, he was defeated by Guy of Namur on Duiveland during the war between the Kingdom of France and the County of Flanders, and he became Duke of Holland shortly after when his father died. Willem was a vassal of the Holy Roman Empire, and he married his daughter Philippa of Hainault to King Edward III of England to gain an alliance with a strong country.